Method and machine for making molded stems for electrical devices



July 13, 1943.

.D S. GUSTIN ETAL METHOD AND MACHINE FOR MAKNG'MOLDED STEMS FORELECTRICAL DEVICES .Fjiled Dec. 1, 1938 3 Sheets-Sheet l mum ATTORNEYJuly 13, 1943 D. s. GUsTlN TAL 2,324,385

METHOD AND MACHINE FOR MAKING MOLDED STEMS FOR ELECTRICAL DEVICES FiledDec. l, 1958 5 Sheets-Sheet 2 w www, f7 W July 13, 1943. D. s. GusTlN ETAx.

3 Sheets-Sheet 3 Filed DGO. l, 1938 Aam/LVM METHOD AND MACHINE FORMAKING MOLDED STEMS FOR ELECTRICAL DEVICES ATTORNEY Patented Giuly i943METHOD AND MACK-EWE FR MAKEIG MLDED STEMS FOR ELECTRICAL DE- VECESDaniel S. Gustn and Henry K. Richardson, Bioorneld, N. 3., assignors toWestinghouse Electric & Manufacturing Company, East littsburgli, Pa., acorporation ci' Pennsylrama Application December l', 1938, Serial No.24l3,356

a claires.

This invention relates to the manufacture of electrical devices, andmore particularly to the molding of the ares, cups or base portionsthereoI,

The principal object of our invention, generally considered, ls themanufacture of electrical devices such as discharge lamps, in which Ythelead-in conductors are made rigid enough to serve as outer contacts orposts in order to dispense with basing, the flares or cups being formedof glass molded therearound to form stems, either by softening andpressing glass blanks, or by pouring molten glass around the leads whileheld in place.

Another object of our invention is the manufacture of electric lamps,especially of the discharge type, in which the Outer electrode leads aremadeso rigid that they are adapted to engage the sockets directlywithout basing, said leads being consolidated directly with glass cupsor ares, electrodes mounted on the inner ends thereof, and the moldedglass then sealed to the bulb proper.

A further object of our invention is the provision of a machine forholding rigid electrode leads and molding glass therearound, whereby thebulb proper may then be directly sealed thereto, with an elimination ofthe usual base.

Other objects and advantages of our invention, relating to theconstruction and arrangement f the various parts, willbecome apparentFigure 4 is an axial sectional view of one of I the blanks used formaking the glass base or flare which holds the heavy leads of adischarge or other electrical device, such as shown in Figure 1.

Figure 5 is an elevational View of one of the heavy leads used in makinga base for a discharge Figure 7 is a fragmentary view corresponding toFigure 6, but showing additional portions of the machine, below theparts shown in Figure 6, the glass blank being shown, in this figure,heated to such an extent that it has softened and owed around the leadssupported on the lower mold element.

Figure 3 is a fragmentary view corresponding to Figure 7, but showing asubsequent position where the upper mold element has been brought downupon the softened glass to mold and consolidate it with the exhaust tubeportion and associated leads.

Figure 9 is a fragmentary view corresponding to Figure 8, but showing asubsequent position in which the upper mold element has been raised,while the upper end of the exhaust tube is opened by the application ofair pressure to blow out the thin wall portion of the glass cupthereabove.

Figure 10 is a View corresponding to Figure 9, but showing a subsequentposition where the glass cup or base has been ejected from the machineby upward pressure on the lower end of the exhaust tube portion thereof.

Figure 1l is a view corresponding to Figure 8, but illustrating theposition of the machine parts when a glass cup or base portion, withoutexhaust tube, is being formed.

Figure 12 is a view corresponding to Figure 6 but showing fragmentaryportions of a machine, modified for forming glass cups or bases frommolten glass.

Figure 13 is a view corresponding to Figure 12, but showing asubsequentv position where the upper mold element has been brought downto press the molten or soft glass into the desired shape, for making aglass cup or base portion for a device such as shown in Figure 1.

Figure 14l is a view corresponding to Figure 13,

but showing a subsequent position where the upper mold element has beenwithdrawn and air pressure admitted to blow a hole in the glass cup toopen the upper end of the exhaust tube portion.

Figure 15 is a, horizontal sectional view of the line XV-XV of`Figure14, in the direction of the arrows.

Figure 16 is a fragmentary vertical sectional view corresponding toFigure 11, but showing another modication.

Figure 17 is a fragmentary view corresponding to Figure 16, but showinga further modification.

Referring to the drawings in detail, like parts being designated by likereference characters, and rst considering Figures 1 to 5 inclusive,

there is shown, as one embodiment of our invention, an electrical deviceof the discharge type, comprising an envelope or bulb 2| in the form ofan elongated hollow cylinder containing some mercury 22L the ends ofsaid enevelope being closed by glass `cups or bases 23 and 24. The cup23 has* incorporated therewith lead-in conductors 25 and 26, while thecup 24 has incorporated therewith lead-in conductors 21 and 28, to formstems, the conductors 25 to 28, inclusive, being so rigid that they areadapted to serve as outer contact posts and eliminate the necessity forthe usual basing.

The inner ends of the leads 25 and 26 carry a filament 29, serving asone electrode, and the inner ends of the conductors 21 and 28 carry asimilar lament 3l, serving as the other electrode. The filaments may beformed of. tungsten or other suitable material, with or without oxidecoating to render them more efficient for the emission of electrons. Theends of the laments 29 and 3i are connected to their lead-in conductorsin any suitable manner, as by means oi' spot welding.

The conductors 25 to 28, inclusive, are formed of suitable material,tungsten and'nickel alloys tbedng mentioned as examples, and the glasssealed therearound is made of such a composition that it will not crackupon cooling around the lead-in conductors. glass is used for the base,then nickel iron, chrome iron, dumet or other alloys of the propercoefficient of expansion are desirably employed as the lead-inconductors. If (Corning code) No.

172 (or hard aluminum borosilicate) or No. 704 or 705 (both soitborosilicate) glass is employed, the lead-in conductors are formed v ofbeaded molybdenum. Or if No. 704 or 705 glass is employed, suchconductors may -consist of Kovar (which is a patented cobalt-nckel-ironalloy) as for application in sodium and mercury vapour lamps. If No, 775or 705 (both soft borosilicate) glass, or-Nonextor No. '172 (or leadborosilicate) glass is used, then beaded tungsten leads are desirablyemployed to match the expansion of said glass.

It will be noted that the cup or base 23 has For example, if soft lplained. The lower mold element 33 may be held in position in a support39 as shown in Figure 7, by means of a set screw'4l. ducted to the lowerend of the tube 38, by means of a rubber tube 42 from a suitable sourceof supply.

The air tube 38, desirably has the upper end of its passage constricted,as indicated at 43, so 'as to eliminate the possibility of glass flowingthereinto, when employed without an exhaust tube. It is normally held inthe position shown in Figure 7 by means of a spring 44, acting between ashoulder 45 on the lower mold element 33 and a collar 46 secured to saidair tube 38,' as by means of a set screw 41, the inner end of whichengages a notch or cavity 48 in said air tube, whichA cavityl is sopositioned that said tube is held with its upper end at the properelevation for supporting a normal length of exhaust tube, so that itsupper end extends to the top of the lower mold element 33, as shown 4inFigures 6 and 7.

In order to provide for raising the exhaust tube 31 to subsequentlyeject the formed cup or base 23 from the mold element 33, the collar 46carries a cam roller 49, actuated by a cam 5l at the proper time toraise the air tube 38, and

. its supported exhaust tube, for ejecting or stripan exhaust tip 32while the cup or base 24 is without such a tip, as it is unnecessary toexhaust at more than one end. 'I'he tip 32 is protected by making thecup reentrant or concave outwardly, and the concave portion of both cups23 and 24 may be finished by lling with a material like sealing wax, ifdesired. The machine to be now described, for making the cups, isemployed a little differently in making the two diierent types. w,

Referring now to the embodiment of our invention, illustrated in Figures6 to 10, inclusive, there are shown portions of one embodiment of amachinel for forming such cups or bases as just described, and themanufacture ot one, such as designated by the reference character 23,with an exhaust tube, will first be disclosed. The machine, as shown inFigure 6, comprises a lower mold elementv33 having pockets or cavi-Vties 34 and 35 in its upper face for receiving heavy lead-in.conductors 25 and 26, such as those designated as forming parts of thecup or glass base 23. The lower mold element 33also has a centralaperture v36 receiving a glass exhaust tube 31, the lower end of whichrests on the upper endof a tube 36, desirably formed of metal andadapted to carry compressed air to said exhaust tube, for a'purpose tobe subsequently ex.

ping the same and the cup molded thereto, from the machine. During thislifting operation, the air tube 38 is guided, not only in the lower moldelement 33, but also in a guiding block 52, secured to the support 39 inany desired manner, as by means of a screw 53. In order to preventturning of the air tube 3B and the cam wheel 49, carried thereby, thecollar 46 desirably carries a guiding'rod 54 depending therefrom, andslidable in the block 52.

Cooperating with the lower mold element 33, is an upper mold element.55, carried on and operated by a rod 56. Operable in the upper moldelement 55 is a plunger 51, for a use to be subsequently pointed out.'Ihe upper mold element carries an annular supplemental mold portion 58,vertically slidable thereon and held in a normally` The mold element 55is provided with pockets or apertures 63 and 64 receiving the upper endsof the leads 25 and 26, sadpockets desirably having their upper endsvented to the atmosphere to v relieve any compression when the mold isclosed,

a`s by means of small apertures 65 and 66.

In order to heat the glass blank 19 and the upper end ofthe exhaust tube31 during the process of forming the glass cup or basefor the device 01' Figure 1, we provide suitable res 61, 68 and 68, issuing from nozzles1I, 12 and 13, carried by piping 14, supplied with suitable combustiblegu from manifold 15, can-led by and rotatable with hollow shaft 16,driven by suitable means so that it rotates on the 'rod 56, andreceivingr a gaseous mixture through registering ports 3l and 3l fromthe hollow lcollar-.11, held against rotation with the shaft 16, andreceiving gas from pipe 13.

Air may be con- The manner of using the machine of Figures 6 to l0inclusive, for making glass cups or bases, such as designated by thereference character 23 is desirably as follows:

The nrst step in the operation, is desirably to place an exhaust tube 31in the lower mold element, where it rests on the upper end of the airtube 33, as shown in Figure 6. The lead-in conductors 25 and 26 are thenplaced in their pockets 34 and 35, in the lower mold element, as shownin the same figure. A section 19 of large diameter glass tubing,corresponding in volume with that of the cup to be formed, is thenplaced on the lower mold element 33 so that it encircles the upper endof the exhaust tube 31 and the lead-in conductors 25 and 2G, as shown inFigure 6.

The res 61, 68 and 69 are then rotated, by turning the hollow shaft 16by any suitable means, not shown, until the glass of the section 19softens and draws around the leads 25 and 2E, as shown in Figure 7. Theaction of the softened glass in wetting the leads 25 and 25 and drawingin around the upper end of the exhaust tube 31, is facilitated by thedirection of ow of the fires B1, 68 and 69, and the surface tension ofthe nearly molten glass.

When the glass becomes suihciently soft, as represented in Figure 7, theupper mold element 55 is brought down to the position represented inFigure 8, -as by a downward movement of its supporting rod 56, causingthe supplemental mold member 58 to telescope with the lower mold element33, engage the annular member 60, and the glass to be pressed into thedesired shape between the upper and lower mold elements 55 and 33, asrepresented in Figure 8. Ihe glass, at the same time, is pressed intoconsolidating engagement with the upper end of the exhaust tube 31, theglass above the exhaust tube opening being thinned by the downwardmovement of the plunger 51, which also insuresl a good seal with theexhaust tube.` l

The next step in the process, is to raise the upper mold element 55,slightly, while leaving the plunger 51 in engagement with the formed cupor base 23, whereby said'base is detached from the upper mold elementand remains resting on the lower mold element 33, both upper moldelement 55 and plunger 51 are then raised out of the way, as shown inFigure 9. The diaphragm or thin section of glass closing the upper endof the exhaust tube 31, as shown in Figure 8, is now broken before theglass has had a chance to harden, by compressed air directed upwardlythrough the exhaust tube, as shown in Figure 9.

The completed base or cup 23, with the exhaust tube 31 sealed thereto,is then ejected or stripped from the lower mold element 33, by anupwardmovement of the air tube 38, as by means of the cam I acting onAthe roller 49 secured thereto, whereupon, an operator may remove the.formed base or cup completely from the machin preparatory to makinganother one.

It will, of course, be understood that in order to make the base or cupforming operation continuous, we desirably have a series of mold ele#ments and associated parts, such as shown in the gures, and cause thesame to move along to rst receive the elements 31, 25,'25 and 19, heatand compress them Yto consolidate and form the base or cup, and thenraise them.for removal, as shown in Figure 10.

Referring now to the embodiment of our invention illustrated in Figure11, there is fragmentarily shown the position of the machinecorresponding with Figure 8, except that the base 3d being theremanufactured is one of the type without an exhaust tip and so, duringthe forming operation, the air pipe 38 is raised so that its upper endis at a level corresponding with that of the top of the exhaust tube 31in Figure '1, where the set screw #il holds it in place, as by 4engagingthe lower notch or cavity el, rather through the air tube 33. Otherwisethe manner of forming the cup or base 25, is identical with that offorming the cup or base 23.

Referring now to the embodiment of our invention, illustrated in Figuresl2 to l5, inclusive, there is shown apparatus modiiiedso as to receivemolten glass rather than an annular glass bodiment. Inl-this instancethe .fires and apparatus for supplying gas are eliminated, but in themain, the other parts of the apparatus may be substantially the same asin connection with the preceding embodiment, except that the lower moldelement 33B, instead of the upper mold element 55a, has a supplementalannular mold member 59a disposed in telescoping relation therewith, andsaid upper molcl element, upon descent, telescopes with said member 58a.

As in the preceding embodiment, the lower mold element 33a rests on asupport 33a and is provided with a central aperture 36a which re.-ceives an exhaust tube 31 supported on a shoulder 82 provided on an airpipe 38a. The upper end of the air pipe is' restricted in diameter so asto fit the exhaust tube 31 and carries an aircontrol valve 83,reciprocating therein, so as to to open the upper end thereof by blowingout a diaphragm of glass, as in connection with the rst embodiment, orclosing said passageway to prevent glass from flowing into the aperturewhen the same is being poured.

As in the iii-st embodiment, the upper mold element 55B has its lowersurface contoured to correspond with the surface `desired on the cup orbase 23`being formed, and carries a plunger 51a used for the samepurpose as the plunger 51 of the rst embodiment. The lower mold element33a is also pocketed as indicated at 34a and 35!I to receive the leads25 and 2B, and the upper mold element has corresponding lead-receivingpockets 63E-64B, vented as indicated at 65i and lilia for a similarpurpose.

mThe only dierence between forming a cup 23 carrying an exhaust tube 31,and one without such a tube, is that if the exhaust' tube 31 is omittedthe aperture 36 is closed in any desired manner, as by using animperforate lower mold element or die otherwise like that designated 33,or by closing the central aperture 36a therethrough, as by means of anair pipe otherwise like that designated 38, but completely lling theaperture 36 and having its upper end closed by a valve or other means.

In order to make the formation of bases or glass cups continuous, wedesirably have a series of molds 33e-#55,l such as shown in Figures 12to' 15, inclusive, and cause the lower mold elements 3321-458BL to moveunder a stream of glass, one by one, to receive the charge required andthen pass on to make way for the next mold element.

After first placing the leads and 26 in the Vlower mold element 33a, asshown in Figure l2, and with or Without the exhaust tube 31 in position,depending upon whether a cup of the type of 23 or that of the type of 24is to be made, the mold element 33a, under consideration, is kept underthe molten glass stream 84 until the glass has risen to the properlevel, or the volume of glass corresponding with that of the cup to beformed, has -been placed in the mold elements 33e-58a as indicated,forexample, in Figure 12.

1n' order 'to accurately predetermine the amount of glass fed to thelower die or mold element 33, we preferably cau'se the moltenY glassstream 84 to issue from al glass melting furnace, not shown, through anorice provided with a die, preferably formed of an alloy of platinum andrhodium, such as described in Patent No. 2,031,083, dated February 1 8,1936, or equivalent material.

rihe temperature of the stream is desirably maintained uniform bysighting a radiation pyrometer, not shown, thereon, and controlling theheat of the furnace by meansof apparatus such as described and claimedin Patent No.

2,116,450, dated May 3, 1938, so that an accurately controlled amount ofglass, just suflcient to ll the mold to the desired extent, is fedthereto, as it passes under the stream 84. P

When the mold has been charged with the desired volume ofr glass and hassurrounded and wet intermediate portions of the leads 25 and 26, wettingandjconsolidating With the upper end of the exhaust tube 31, if used, itis cut off by moving the mold vfrom thereunder, or in any desiredVmanner, and the upper mold element 55a is then brought down intoengagement with the glass to formv the same, the central plunger 51abeing depressed to thin the central portion of the formed cup,especially if it is one with an exhaust tube.

The 'next step is to raise the upper mold element 55a slightly, whileleaving the plunger 51a in engagement with the formed cup or base 23 or24, as the case may be, whereby said base is devention illustrated inFigure 16, there are shown fragmentary portionsof apparatuscorresponding with that of Figures 12 to 15, inclusive, except that hereprovision ls made for only making cups provided with exhaust tubes.- Themain distinction between the machine of Figure 16 and 33b and asupplemental annular mold member 58h, supported as heretofore. The moldmember 33b is formed with a simple aperture 35h which receives anexhaust tube 31 supported in any desired manner, as on an ejector orstripper member, a ledge or a shoulder, not shown. No necessity arisesin the present instance of having an air pipe corresponding with thatdesignated as 38*il in the preceding embodiment, as the upper end of theexhaust tube 31 is kept open by the lower, preferably tapered, end of aplunger 51%, moved to the position illustrated in Figure 16 before theupper mold 55b moves downwardly to its illustrated position.

As in the preceding embodiment, the upperl i mold element 55b has itslower surfacecontoured to correspond with the upper surface desired onthe cup or base 23 to be formed, and the plunger 51b moves axiallythereof and is used for a purpose corresponding with that of the plunger51 except, as previously mentioned, it also dispen'ses with thenecessity of blowing` out the upper end of the exhaust tube by air. Thelower mold element 33b is pocketed as indicated at 34b and 35.b toreceive the leads 25 and 26, and the upper mold element hascorresponding lead-receiving pockets 63b and 64b, desirably vented as inthe preceding embodiment.

tached from the upper mold element and remains resting on the lower moldelement 33a. Both the upper mold element a and the plunger. 51"L arethen raised out of the way to leave the upper surface of the molded cupfree, as shown in Fig- -ure 14. The diaphragm or thinned section ofglass,` closing the upper end of the exhaust tube 31 as a cup 23 isbeing formed, is now broken, `before the glass has hardened, bycompressed air directed upwardly through the exhaust tube, as shown inFigure14.

haust tube opening operation.

The completed base or cup 23 or 24, as the case maybe, is then ejectedor stripped from the lower mold element 33a and forced out of the sur-If a cup 24 is being formed it is, of course, unnecessary to performthis ex-l The operation of apparatus in accordance with Figure 16 isalmost identical with that of the apparatus of Figures 11 to'15,inclusive. After rst placing the leads 25 and 26 in the lower moldelement 33bas shown in Figure 16, and placing the exhaust tube 31 in theposition illustrated, the lower mold element is kept under a stream ofmolten glass, as in the preceding embodiment, until glass `has risen tothe proper level, or the volume of glass corresponding with that of thecup to be formed, has been placed in the mold elements 33h-5811,' asshown in Figure 12 in connection with the preceding embodiment.

As in said preceding embodiment, the amount of glass is desirablyaccurately predetermined by using a die formed of a material such as analloy of platinum and rhodium, as described in Patent No. 2,031,083,previously referred to, the temperature of the stream being desirablymaintained by using control apparatus as described and claimed 4inPatent No. 2,116,450, also previously referred When the mold has beencharged with the desired volume of glass which has surrounded and wetintermediate portions of the leads 25 and 26 and consolidated with theupper end of the exhaust tube 31, the stream of glass is cut voff, as bymoving the mold from thereunder or then brought down into engagementwith the top surface of the glass to form the same, as in the precedingembodiment.

The next step is to raise thev upper mold element 55b slightly, whileleaving the plunger 51 in engagement with the formed cup or base 23,whereby said base is detached from the upper mold element and remainsresting on the lower mold element. Both the upper mold element 55b andthe plunger 51 are thenmoved out of the way to leave .the upper surfaceof the molded cup free, as shown, for example, in connection with thepreceding embodiment in Figure 14, except that in the present instance,there isfno further step performed besides removing the formed base fromthe lower mold element 33. Such removal may be accomplished either bypulling up on the leads and/or 25, or by pushing up on the exhaust tube31. Although the use of anexhaust tube opening prong has been shown onlyin connection with the use of molten glass supplied in a stream, it willbeC understood that it v may also be used in connection with apparatusas disclosed in Figures 1 to 10, inclusive.

Referring now to the embodiment of our invention illustrated in Figure17, there are shown fragmentary portions of apparatus corresponding withthat of Figure 16, except that the use of an initially separate exhausttube 31 is obviated.

As-in the embodiment of Figure 17, we have a lower mold element 33 and asupplemental annular mold member 58, desirably supported as heretofore.The mold member 33 is formed with an aperture 36 in which the exhausttube is formed from molten glass, as will presently be described.

The upper mold element 55 has its lower surface contoured to correspondwith the upper surface desired on the cup or base 23 to be formed. Theplunger 51 moves axially thereof and has a reduced extension 51 fittingin the aperture with clearance corresponding with the desired thicknessof the Aexhaust tube portion 31 to be formed on the base 23. The lowermold element 33 is pocketed, as indicated at 34 and 35, to receive theleads 25 and 26, and the upper mold element 55 has correspondinglead-receiving pockets 63 and 64., desirably vented as indicated at 65and 66.

The operation of apparatus in accordance with Figure 17 is almostidentical with that of the apparatus of Figure 16. After first placingthe leads 25 and 26 in the lower `mold element 33, said mold element iskept under a stream of molten glass, as in the preceding embodiment,until glass has risen to the' proper level, or a volume of glasscorresponding with that ofthe cup and integral tapered exhaust tubeportion to `be formed has been placed in the mold elements 33-58, asshown in Figure 12in connection with va. preceding embodiment.

As in the preceding embodiments, the amount of glass is desirablyaccurately predetermined by using a. die for-med of a material such asan alloy of platinum and rhodium, as described in Patent No. 2,031,()83previously referred to, the temperature ofthe stream being desirablymaintained by using control apparatus as described in Patent No.2,116,450, also previously referred to.

When the mold has been charged with the desired volume of glass, whichhas surrounded and wet Yintermediate portions of the leads 25 and 1 26,and lhas just started to overow into` the aperture 36, the stream ofglass is cut oi, as

by moving the lower mold element from thereunder, or in any desiredmanner, and the central plunger 51 and upper mold element 55 start todescend to finally reach the position illustrated in Figure l7. Themovement of these elements is preferably not at the same rate of speed,`the upper mold element 55 desirably rst reaching the positionillustrated, where it causes the level of the glass in the mold elements33-58 to rise, thereby providing suicient glass to be acted onimmediately by the descending plunger 51, land particularly the reducedextension 51 thereof, to form the exhaust tube portion 31 asillustrated.

The next step is to raise vthe upper mold element 55 slightly, whileleaving the plunger 51 in engagement with the formed cup or base 23,

whereby'saidbase is detached from the upper mold element and remainsresting on the lower mold element. Both the upper mold element 55 andthe plunger 51 are then moved out of the way to leave the upper surfaceof the molded cup I free, as shown, for example, in connection with apreceding embodiment in Figure l14, except that in the present instancethere is no'further step necessary besides removing the formed cup orbase 23. Suchremoval may be accomplished either by pulling up on theleads 25 and/or 26,

- or by pushing up on the exhaust tube 31.

' -From the foregoing disclosure, it will be seenthat we have devised anovel form of glass stem, base. or cup, particularly adapted fordischarge devices, although suitable for other electrical devices, andimproved forms of apparatus, especially adapted for molding such cups orother similar devices, either from softened glass blanks or directlyfrom molten glass, thereby avoiding some subsequent steps usuallyperformed. The cups, as formed have incorporated therewith, rigid prongshaving the double function of lead-in conductors and outer contactmembers, thereby enabling us to dispense with a Isubsequent basingoperation.

Although preferred embodiments of our invention have been disclosed, itwill be understood that modifications may be made within the spirit andscope of the appended claims.

We claim:

1. A machine for making stems for electrical devices, comprising a lowermold element with cavities for receiving the lower portions of rigidlead-in conductors, an upper mold element having downwardly openingcavities for receiving the upper portions of said conductors, and aplunger operating in said upper mold element, in order to provide forstripping the formed stems therefrom 2. A machine for making stems forelectrical devices, comprising a lower mold element having a centralaperture`for receiving an exhaust tube and an air tube therebelow forfurnishing air pressure to said exhaust tube and serving as a stoptherefor, said lower mold element also havv ing pockets for receivingthe lower portions of cavities for receiving the lower portions of rigidlead-in conductors, an upper mold element having downwardly openingcavitiesy for receiving v devices, comprising a lower mold element withcavities for receiving the lower portions of rigid lead-in conductorsand an aperture for receiving 'an exhaust tube, a plunger reciprocablein said aperture for moving an exhaust tube when positioned therein, anupper mold element having downwardly opening cavities for receiving theupper portions of said conductors, and a plunger operating in said uppermold element for stripping stems therefrom when formed.

5. A machine for making stems for electrical devices, comprising a lowermold element with cavities for receiving the lower portions of rigidlead-in conductors and an aperture for receiving an exhaust tube, aplunger reciprocable in said aperture for moving an exhaust tube whenposi tioned therein, said plunger being hollow for supplying compressedair to said tube for making an exhaust aperture in a stem beingconstructed, an upper mold element having downwardly opening cavitiesfor receiving the upper portions of said conductors, and a plungeroperating in 'said upper mold element for stripping stems therefrom whenformed. 1

6. A machine for making stems for electrical devices comprising a lowermold element with cavities for receiving the lower portions of lead-inconductors, an upper mold element having downwardly opening cavitiesforv receiving the upper portions of said conductors, a plungeroperating in said upper mold element to p'rovide for stripping formedstems therefrom,and another plunger operating in'the lower mold elementto raise formed stems therefrom.

7. The method ot making a stem for an electrical device comprisingpositioning the lower portionsof lead-in conductors lin a lower moldelement, depositinga desired quantity of softened glass around saidconductors, forming said glass by the descent of an upper mold elementpocketed toreceivethe upper portions of said conductors, causingrelative'movement between said upper mold 'element and a plungeroperating therein to strip formed stems from said upper mold element,and raising the formed stems from said lower mold element by a plungeroperating in the latter.

8. 'Ihe method of making a Vstem for -an electrical device, comprisingpositioning lead-in conductors in a lower mold element, depositing adesired quantity of softened glass' around said conductors, forming saidglass by the descent of an upper mold element, depressing a plunger,operating in said upper mold element, to thin a central portion of saidglass, raisingV said upper mold element to cause the formed stem to bestripped therefrom by said plunger,`raising saidl plunger, and ejectingthe formed stem` from said lower mold element by another plungeroperating therein.

DANIEL S. GUS'IIN.

HENRY K. RICHARDSON.

